A hanger rod is part of a typical hanger assembly wherein one end of a threaded rod is vertically attached to the building structure and the other end has an attachment mechanism such as a yoke which is used to connect to the part that is to be supported such as water pipes. While these rods can be provided in any diameter, the typical size is either ⅜, ½, ⅝, ¾, ⅞, 1 or 1¼ depending on the structure that is to be supported. The lengths can be selected as needed for the particular construction project with less than 120 inches being typical.
Various structures and methods have been proposed to strengthen the hanger rod against deformation due to unusual stresses. Most of such devices make use of a stiffening channel strut, angle iron or pipe that is positioned substantial parallel to the hanger rod. Connection of the stiffening member can be provided by actually welding the member to the rod, however, this is extremely time-consuming and not practical due to the expense involved.
U.S. Pat. No. 6,783,104 discloses and claims a deformable clip that connects the stiffening pipe to the hanger rod. This device has the advantage of being low cost and relatively easy to install. However, testing by the inventors have found that this arrangement will buckle quite easily unless the location of the holes are held to very close tolerances contrary to the teachings found in the '104 patent. The '104 patent teaches the use of a carriage bolt to tighten the clip in place. Further, the use of a carriage bolt prevents the legs of the clip from being tightened against one another. This device requires that the stiffening pipe to be placed between the hanger rod and the attachment mechanism. The design flaws in this device result in clip failure unless a substantial greater number of them are utilized.
U.S. Pat. No. 4,141,107 issued to Shiman et al. on Feb. 27, 1979 discloses a clip attaching a single round member using a clip that is bent in place around the single round member attaching it to the surface.
U.S. Pat. No. 1,362,244 issued to Farley on Aug. 8, 1919 discloses a “U” shaped hanger assembly that does not have a hanger rod.
U.S. Pat. No. 2,872,141 issued to Hefner on Feb. 3, 1959 discloses a preformed round “O” shaped cable hanger that is designed to hold a single cable.
A hanger rod stiffening clip that can be easily attached, is inexpensive to produce and can be spaced at 24 inch clip spacing for ⅜ inch hanger rod from one clip to the next along the stiffening pipe, which is equal to the governing least radius of gyration ratio for ⅜ inch hanger rod to resist buckling, and can withstand compression force of at least 325 pounds on a test apparatus using a 120 inch long hanger rod in a typical installation, is not found in the prior art. A ⅜ inch hanger rod that is 24 inch long and is tested without stiffening clips will buckle at 125 pounds of compression pressure on the test apparatus.